Southern Africa’s New Mega-Carnivore: A Whole Lotta Dinosaur

By Gemma Tarlach | October 25, 2017 1:00 pm
CAPTION HERE (Credit Fabian Knoll and Lara Sciscio)

Known so far only from its giant footprints, a new Southern African mega-carnivore is believed to be the region’s largest dinosaur predator ever. (Credit Fabian Knoll and Lara Sciscio)

My, what big feet you have…200-million-year-old dinosaur footprints found in the mountainous Southern African country of Lesotho are unique within the Southern Hemisphere and the largest of their kind ever discovered on the continent. But size isn’t the only thing that matters about the mega-carnivore that made them.

The footprints, each measuring about 22 inches in length, were discovered on a layer of rippled, fine-grained sandstone dated to about 200 million years ago. The ripples and other features preserved in the rock suggest it was once part of a seasonal watering hole or edge of a river channel. Other tracks from smaller theropods — bipedal, typically carnivorous dinosaurs — were found around the mega-carnivore’s trackway.

Based on what we know about theropod proportions from fossil skeletons, the size of the Lesotho footprints suggests the mega-carnivore was about 30 feet long and as tall as ten feet at the hip. Okay, that’s not as big as the most famous theropod, 40-foot-long (or so) T. rex, but it is big enough to ruin the day in a bitey way for pretty much anything else in the neighborhood.

CAPTION HERE (Credit Fabian Knoll)

University of Manchester paleontologist Fabien Knoll provides some scale beside the impressive mega-carnivore footprints described today. (Credit Fabian Knoll)

Lower Jurassic Park

Aside from finding such a large theropod so far south in Africa (famously big and bitey theropods such as Carcharodontosaurus and Spinosaurus are well known from the northern half of the continent), what’s exciting about the new mega-carnivore is how old it is. Carcharodontosaurus and Spinosaurus are both Cretaceous critters, but this guy is about twice as old.

I say “this guy” because researchers have tentatively named whatever made the trackway Kayentapus ambrokholohali and I’m too lazy to keep typing that knucklebuster of a species name over and over. Kidding. K. ambrokholohali is not an official species yet, given the whole habeas corpus thing about formal classification: For now, “Ambro” is technically an ichnospecies, known only from trace fossils (which in this case is the trackway).

Sidenote: “Ichnospecies” is a fantastic word to have in your back pocket the next time you play Hangman or Scrabble if you want people to find you insufferable.

Back to Ambro. The theropod lived during the Early Jurassic, aka Lower Jurassic, a time when dinosaur populations in general were recovering following the mass extinction that marked the end of the Triassic Period, about 201 million years ago. While the end-Triassic isn’t as well-known as the end-Cretaceous (very bad, especially for dinosaurs that weren’t birds) or the end-Permian (very, very bad for everybody), it was pretty rough, and wiped out about three-quarters of species around at the time.

Other theropods found from this earliest of the Early Jurassic tend to be fairly small, with the largest maxing out at about 18 or 19 feet. Paleontologists have found a theropod track, about the same age and almost as large as Ambro’s prints, in Poland. That suggests there may have been large carnivores tromping about Northern Hemisphere in the Early Jurassic. But no one would expect a theropod the size of Ambro to be out and about, especially in Southern Africa, at the time. Based on skeletal fossils, we thought theropods in general underwent a big bulk-up in body size only millions of years later in the Jurassic Period.

The Embiggening

There have been a few theories about why carnivores may increase in size following an extinction event. A mass die-off can wipe out a lot of the predators’ competition, for example. Other post-extinction event changes in local ecosystems, such as changes in temperature, aridity or vegetation, may, at the same time, create an environment for the carnivores’ prey to thrive and get bigger both in terms of individual size (more meat!) and population (more opportunities to catch that meat!).

Still, the sheer size of K. ambrokholohali‘s tracks, laid down so soon after the end-Triassic (geologically speaking), suggests that mega-carnivores were around much earlier than we thought, perhaps because they survived the extinction event unscathed or found the environment that emerged in its wake a perfect opportunity for growth.

Ichnospecies Ambro makes its debut today in PLOS ONE.

The mountainous Southern African country of Lesotho, seen on the horizon, is home to some of the continent's most intriguing dinosaurs. (Credit G. Tarlach)

The mountainous Southern African country of Lesotho, seen on the horizon, is home to some of the continent’s most intriguing dinosaurs. (Credit G. Tarlach)

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  • OWilson

    Incredible footprints but wouldn’t a 25 ton beast sink further into the soft sand and leave big deep holes?

    These look like sparrow tracks! :)

    Man made?

    • GemmaTarlach

      What?! 25 tons!? Yikes. Consider that estimates of the body weight of a large T. rex, much larger than this guy, are only about 9 tons. I take your point more generally, however. The researchers did not provide an estimate of body weight for the ichnospecies, but let’s consider a large African elephant, which probably weighs around 7 tons. Anecdotally, I have seen the tracks these animals leave on both the hard sand of a dried-up watering hole edge and the wetter goo of a river bank and they can be surprisingly shallow given the animal’s mass. So no, I don’t think the lack of depth in the prints suggests anything shady. It’s a pretty interesting paper, by the way, and fairly accessible — it’s also open access, so you might enjoy giving it a read.

      • OWilson

        I got my weight estimate from your article where you compared it to “famously big” Spinosaurus. The latest (2007) estimate for that was 21 Metric Tons, or about 24 of the U.S. tons I am familiar with.

        Anyway, whatever, my real point was the shallow impression, of the bird-like prints.

        We know that elephants and camels have relatively large pads at the bottom of their feet, which prevents them sinking into mud and sand, and there are lots of web photos showing these broad pad impressions.

        There’s no pad impression around these relatively thin and delicate claw like prints, you would expect in sand from even a 10 ton beast.

        Not being argumentative. Just an observation.

        Thanks for another interesting article.

        • GemmaTarlach

          No worries…if I thought you were just being argumentative I would have ignored you :-) …btw, Spinosaurus was a *lot* bigger than this guy, but I’m not sure where you got the 21 metric tons number. I did a quick general search of that figure and what came up was Wikipedia which isn’t what I’d call a great source [understatement]. The latest estimates for Spino in peer-reviewed research (2013 and 2014) are 9 to 20 tons (not metric tons), and I suspect that 20 is a significant overestimation. Re: the rest, you’re right, the foot shape of animals such as an elephant is obviously very different. My point was that an animal with a large mass does not necessarily leave deep prints. Theropods did have pads on the bottoms of their feet, and there are pad impressions from the tracks discussed in the paper. Again anecdotally, having seen ostrich prints (closer to the theropod shape but obviously much smaller than this guy) up close I’ve been struck by how light they are in proportion to the bird’s size. Gotta get back to footnoting my upcoming feature so I can send it to fact check before the weekend, but thanks for the exchange.

          • OWilson

            Grasias!

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  • Mike Richardson

    Seems more in the size range of an allosaur, but an earlier arrival. Did the footprints give enough detail to speculate on the possible the therapod group?

    • GemmaTarlach

      The thing about theropod tracks is that the lineage sorted out a general ideal foot shape early on and pretty much stuck with it until very late in the game (of course that is a gross generalization but compared with changes in foot shape that we see within our own lineage over the past, say, 4 million years — a blink of the eye in Dino-time —yeah, that’s about the size of it). That said, the team did, as you might image, scrutinize each track a number of different ways, including analyzing the shape of the heel imprint (basically, a U- or V-shape). Without an actual fossil to really understand its anatomy, there is only so much they can determine, but they did put it in the Kayentapus ichnogenus, known only from other trace fossils. As I mentioned above, the paper is open access so you might want to skim it and see how they approached the analysis. (I love it when papers are open access because I think it’s worth it for any curious reader to give it a whirl, not only to get a fuller sense of the research, but often to find details of particular interest that I can’t cover in a blog post of this length.)

      • Mike Richardson

        Thanks for the info! I’ll give it a look.

      • Wayne Higgs

        The weight of the animal seems irrelevant when you consider the age of the tracks, 200 million years of erosion and very little idea on the state of the substrate in which the tracks were left. Far more relevant is the size of the prints from which an estimate of size of the animal can be drawn. Thank you for the interesting article, which I enjoyed immensely.

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